Nanostructures such as multi-walled carbon nanotubes have a wide variety of different applications due to their electrical conductivity and strength characteristics. These can be formed from a wide variety of different materials. One of the most basic materials used to form multiple-walled carbon nanotubes is coal. Carbon nanotubes in particular have been formed from coal using arc discharge, and CVD.
Carbon nanotube production is increased when metal catalysts are added to the arc discharge electrode, i.e., cobalt, iron, nickel, yttrium, lanthanum, gaddinium, and boron. Since nanotube synthesis takes place at higher temperatures, a complete decomposition of the catalytic precursor is expected which acts as a nucleation agent to enhance growth of the carbon nanotubes.
Coal has certain disadvantages in the formation of multiple-walled carbon nanotubes. Typically, in order to produce carbon nanotubes from coal it is necessary to produce coal rods in which the catalysts are in the rod. It is also necessary to operate the system at relatively high temperatures, above 2000° C. Furthermore, coal (bituminous and sub-bituminous) still contains hydrogen which, if extracted from the coal before the production of the nanostructure, will provide an economic benefit. In addition, expensive catalysts must be added to the coal mixture in order to allow the formation of the carbon nanotubes.